Mozilla

Mozilla

Mozilla Foundation Security Advisory 2011-43

loadSubScript unwraps XPCNativeWrapper scope parameter

Announced
September 27, 2011
Reporter
David Rees
Impact
Critical
Products
Firefox, SeaMonkey
Fixed in
  • Firefox 7
  • SeaMonkey 2.4

Description

David Rees reported that the JSSubScriptLoader (a feature used by some add-ons) was "unwrapping" XPCNativeWrappers when they were used as the scope parameter to loadSubScript(). Without the protection of the wrappers the add-on could be vulnerable to privilege escalation attacks from malicious web content. Whether any given add-on were vulnerable would depend on how the add-on used the feature and whether it interacted directly with web content, but we did find at least one vulnerable add-on and presume there are more.

The unwrapping behavior was a change introduced during Firefox 4 development. Firefox 3.6 and earlier versions are not affected.

References